X-ray and time-of-flight (TOF) neutron diffraction and Raman spectroscopic measurements have been carried out at 25°C on concentrated aqueous sulfuric acid solutions, (H₂SO₄)_x(H₂O)_1-x, x = 0, 0.25, 0.5, 0.75 and 0.86, in order to investigate the hydrogen-bonded intermolecular structure in the solutions. The intramolecular parameters for regular tetrahedral SO₄ unit were determined from the least squares fit to observed X-ray and neutron interference terms in the range of Q 8 ^-1. The nearest neighbor intermolecular hydrogen-bonded distances, r_o...o = 2.7and r_o...o = 1-7 , respectively determined from X-ray and neutron intermolecular distribution functions, exhibited both 0.2shorter values than those reported for pure liquid water. The isotropic Raman spectra of O-H stretching region for solutions of higher H₂SO₄ content (x 0.5) indicated an extremely broadened band centered at 3030 cm^-1, which corresponds to 300 cm^-1 lower frequency shift compared with that for pure liquid H₂O. These results suggest the existence of strong hydrogen-bonded intermolecular interaction in these solutions.